modular synth case

I am interested in jumping into the world of analog synths with AS's French Connection. Their modules look very nice for completing my starter system, but their cases seem way too expensive. I remember a few years back I built a PC from parts and searched around for cheap cases, and there was a big price range, and I ended up with one that was about $30. Does anyone know where to get good deals on the kind of "motherboard" and power supply needed for a modular synth? I might just build a case myself to house that stuff, but any ideas on where to get one of those would be appreciated as well. (Could you modify a standard PC tower case perhaps?)